What do people with bile duct cancer die from in the end stages?

I know this may sound like an uncomfortable topic. I have to ask because my father had bile duct cancer and died. His death certificate indicates it was "Complications of Bile Duct Carcinoma."

While he did have bile duct cancer, I don't believe he died from cancer or complications of Bile Duct Carcinoma.

First, he had resectable bile duct cancer, meaning it was only in his bile duct, it was small and had not metastasized (not gone beyond his bile duct to his lymph nodes or other organs). So he was an ideal candidate for surgery.

Secondd, the operation confirmed it had not traveled past the bile duct and the tissues submitted for post op lab testing indicated they got all the tumor.

He was doing well and expected to go home three days post op. The dr said "The expectation is not that he recover, it’s that he should recover fully. Just a couple of days."

He was ambulating and beginning to eat eat soft foods and was going to proceed to solid foods.

He was 82 and had a history of diabetes and a quintuple bypass heart surgery in his 60s. He was of normal weight.

But things changed
He contracted Clostridium difficile while in the hospital. He developed severe dehydration. He was given antibiotics which made the diarrhea worse.

As a result of the dehydration he became disoriented. In his disoriented state, he would pull out is IV. Someone else made the decision to refuse any more treatment for his dehydration and signed a Do Not Resuscitate form.

He died 4 weeks after a successful bile duct cancer resection.

At the time of his death, the only thing being tested was his creatinine levels which were above normal indicating he was still in the state of dehydration as he did not have any kidney problems and should have had a normal creatine level otherwise.

My main question is:

Is Clostridium difficile a complication of Bile Duct Carcinoma?